Former Socceroos captain Ned Zelic believes Tom Rogic can showcase his amazing skills on football's biggest stage and be Australia's X-factor at the World Cup.

Rogic is a certainty to have his name read out on Wednesday when Socceroos coach Ange Postecoglou unveils his preliminary 30-man squad for the World Cup.

However, fellow Canberra product Carl Valeri is considered only an outside chance of earning selection after missing almost 12 months with an ankle injury and struggling for game time with his Italian club.

While a groin injury disrupted the end of his A-League season with Melbourne Victory, Rogic has shown enough flashes of brilliance in his nine caps with the national team to be the attacking weapon the Socceroos need if they're any chance of progressing out of a difficult group in Brazil.

Advertisement

The Socceroos will be rank underdogs up against Spain, the Netherlands and Chile, but Zelic warned against looking ahead to next year's Asian Cup in Australia instead.

Zelic - now an expert commentator with SBS - believes Rogic can overcome a season where he didn't get much game time at Scottish giants Celtic before an up-and-down stint with the Victory on loan.

''Tommy's the type of player that can go through a difficult bad patch, but can flick the light switch on,'' Zelic said.

''In saying that, he really next season has to get himself organised club wise and get himself playing somewhere regularly.

''The most important thing for him is to be physically fit and the rest will come.''

Valeri is highly unlikely to get picked for his second straight World Cup as the 29-year-old midfielder continues his way back from a serious ankle injury.

He isn't earning regular playing time with his Italian Serie B club, Terana and was an unused substitute in his team's 2-0 loss to Latina on the weekend.

"It's difficult for Carl now - the fact he's had so many injuries and the fact he hasn't been playing that regularly,'' Zelic said.

''I think it's going to be difficult.

''It's a tournament where you have to be fit and prepared, otherwise you'll get shown up by the others.''

Zelic didn't expect there to be too many surprises in the Socceroos squad as Postecoglou has been consistent with the standards he has set since taking over from Holger Osieck last year.

Former captain Lucas Neill has been squeezed out because of a lack of playing time at club level, while Brett Holman has retired from international football.

Zelic said the biggest danger for the Socceroos was putting too much focus on next year's Asian Cup.

''This is a World Cup and it's the biggest tournament in football. Let's concentrate on really trying to do well here instead of looking at this is an opportunity for others to impress,'' he said.

"The last thing you want is to be embarrassed on the world stage.

''We want to put the best team out on the park irrespective of if they're going to be around for the Asian Cup.

''We've got to play to our strengths and send a message to the other teams that if you're going to beat us it's not going to be easy.''